IIIc. Moraine of the Third Glaciation—Riss.

The section of the Rheinfelder Hill lies 3 km. west from the Möliner Field.

More remote from the glacial regions, but equally subject to the inundations of glacial times are the 'high terraces' along the River Seine, which are ninety feet above the present level of the river and contain the remains of mammals characteristic of the First Interglacial Stage, such as the southern elephant (E. meridionalis), while the 'low terraces' along the Seine are only fifteen feet above the present level of the river and contain mammals belonging to the Third Interglacial Stage. Similarly, the 'high terraces' of the River Eure contain mammals of First Interglacial times, such as the southern elephant (E. meridionalis) and Steno's horse (E. stenonis); these fossils occur in coarse river sands and gravels which were deposited by a broad stream that flowed at least ninety feet above the present waters of the Eure.

The human interest which attaches to these dry facts of geology appears especially in the valleys of the Somme and the Marne in northern France; here again we find 'high terraces,' 'middle terraces,' and 'low terraces'; the latter are still subject to flooding. In the deep gravels upon each of these terraces we find the first proofs of human residence, for here occur the earliest Pre-Chellean and Chellean implements associated with the remains of the hippopotamus, of Merck's rhinoceros, and of the straight-tusked elephant (E. antiquus), together with mammals which are characteristic both of Second and Third Interglacial times.

This raises a very important distinction, which is often misunderstood; namely, between the materials composing the original terraces and those subsequently deposited upon the terraces. It appears to be in the latter that human artifacts are chiefly, if not exclusively, found.

Times of the Loam Stations

The 'loam' which washes down over the original sand and gravel 'terraces' from the surrounding hills and meadows is of much later date than the 'terraces' themselves, and the archæologist in the valley of the Somme as well as in that of the Thames may well be deceived unless he clearly distinguishes between the newer deposits of gravels and of loams and the far older gravels and river sands which compose the original 'terraces.' This is well illustrated by the observations of Commont on the section of St. Acheul.[(56)] The loams and brick-earth are of much more recent age than the original gravels and sands of the 'terraces' which they overlap and conceal; the lowest and oldest 'loam' (limon fendillé) contains Acheulean flints, while the overlying 'loam' contains Mousterian flints. Although occurring on the 'higher terraces,' these flints are of somewhat later date than the primitive Chellean flints which occur in the coarse gravels and sands that have collected upon the very lowest levels (Fig. 59).

A similar prehistoric inversion doubtless occurs in the 'terraces' of the Thames, for materials on the 'highest terrace' (Fig. 8) contain Acheulean flints, while materials on the 'lowest terrace' belong to a much more recent age.

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